package main

func solve(str string) string {
    runes := []rune(str)
    n := len(runes)
    if n == 0 {
        return ""
    }
    for i := 0; i < n/2; i++ {
        j := n - 1 - i
        runes[i], runes[j] = runes[j], runes[i]
    }
    return string(runes)
}